simpson

0th

Percentile

Simpson's diversity index

Simpson's diversity index

Keywords
math
Usage
simpson(x)
Arguments
x
Ecosystem vector; coerced to class count
Details

Returns the Simpson index $D$: the probability that two randomly sampled individuals belong to different species. This is $$1-\sum_{i=1}^S\left(p_i\right)^2$$

where $p_i$ is the relative frequency of the $i^{\rm th}$ species

Note

Early versions of the untb package effectively defined $D$ as the probability that two randomly selected different individuals belong to different species

References

  • S. P. Hubbell 2001.The Unified Neutral Theory of Biodiversity. Princeton University Press.
  • F. He and X.-S. Hu 2005.Hubbell's Fundamental Biodiversity Parameter and the Simpson Diversity Index. Ecology Letters, volume 8, pp386-390. doi:10.1111/j.1461-0248.2005.00729.x
  • E. H. Simpson 1949.Measurement of diversity. Nature, volume 163, p688

See Also

preston

Aliases
  • simpson
Examples
data(butterflies)

D <- simpson(butterflies)
theta <- optimal.prob(butterflies)*2*no.of.ind(butterflies)

#compare theta with D/(1-D) (should be roughly equal):

theta
D/(1-D)
Documentation reproduced from package untb, version 1.3-3, License: GPL

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